drivers/s390/char/sclp_tty.c - arm/linux-arm64-legacy - Git at Google

 /*
  *  drivers/s390/char/sclp_tty.c
  *    SCLP line mode terminal driver.
  *
  *  S390 version
  *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
  *    Author(s): Martin Peschke <mpeschke@de.ibm.com>
  *		 Martin Schwidefsky <schwidefsky@de.ibm.com>
  */

 #include <linux/module.h>
 #include <linux/kmod.h>
 #include <linux/tty.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
 #include <linux/sched.h>
 #include <linux/wait.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <asm/uaccess.h>

 #include "ctrlchar.h"
 #include "sclp.h"
 #include "sclp_rw.h"
 #include "sclp_tty.h"

 #define SCLP_TTY_PRINT_HEADER "sclp tty driver: "

 /*
  * size of a buffer that collects single characters coming in
  * via sclp_tty_put_char()
  */
 #define SCLP_TTY_BUF_SIZE 512

 /*
  * There is exactly one SCLP terminal, so we can keep things simple
  * and allocate all variables statically.
  */

 /* Lock to guard over changes to global variables. */
 static spinlock_t sclp_tty_lock;
 /* List of free pages that can be used for console output buffering. */
 static struct list_head sclp_tty_pages;
 /* List of full struct sclp_buffer structures ready for output. */
 static struct list_head sclp_tty_outqueue;
 /* Counter how many buffers are emitted. */
 static int sclp_tty_buffer_count;
 /* Pointer to current console buffer. */
 static struct sclp_buffer *sclp_ttybuf;
 /* Timer for delayed output of console messages. */
 static struct timer_list sclp_tty_timer;
 /* Waitqueue to wait for buffers to get empty. */
 static wait_queue_head_t sclp_tty_waitq;

 static struct tty_struct *sclp_tty;
 static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
 static unsigned short int sclp_tty_chars_count;

 struct tty_driver *sclp_tty_driver;

 extern struct termios  tty_std_termios;

 static struct sclp_ioctls sclp_ioctls;
 static struct sclp_ioctls sclp_ioctls_init =
 {
 	8,			/* 1 hor. tab. = 8 spaces */
 	0,			/* no echo of input by this driver */
 	80,			/* 80 characters/line */
 	1,			/* write after 1/10 s without final new line */
 	MAX_KMEM_PAGES,		/* quick fix: avoid __alloc_pages */
 	MAX_KMEM_PAGES,		/* take 32/64 pages from kernel memory, */
 	0,			/* do not convert to lower case */
 	0x6c			/* to seprate upper and lower case */
 				/* ('%' in EBCDIC) */
 };

 /* This routine is called whenever we try to open a SCLP terminal. */
 static int
 sclp_tty_open(struct tty_struct *tty, struct file *filp)
 {
 	sclp_tty = tty;
 	tty->driver_data = NULL;
 	tty->low_latency = 0;
 	return 0;
 }

 /* This routine is called when the SCLP terminal is closed. */
 static void
 sclp_tty_close(struct tty_struct *tty, struct file *filp)
 {
 	if (tty->count > 1)
 		return;
 	sclp_tty = NULL;
 }

 /* execute commands to control the i/o behaviour of the SCLP tty at runtime */
 static int
 sclp_tty_ioctl(struct tty_struct *tty, struct file * file,
 	       unsigned int cmd, unsigned long arg)
 {
 	unsigned long flags;
 	unsigned int obuf;
 	int check;
 	int rc;

 	if (tty->flags & (1 << TTY_IO_ERROR))
 		return -EIO;
 	rc = 0;
 	check = 0;
 	switch (cmd) {
 	case TIOCSCLPSHTAB:
 		/* set width of horizontal tab	*/
 		if (get_user(sclp_ioctls.htab, (unsigned short __user *) arg))
 			rc = -EFAULT;
 		else
 			check = 1;
 		break;
 	case TIOCSCLPGHTAB:
 		/* get width of horizontal tab	*/
 		if (put_user(sclp_ioctls.htab, (unsigned short __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSECHO:
 		/* enable/disable echo of input */
 		if (get_user(sclp_ioctls.echo, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGECHO:
 		/* Is echo of input enabled ?  */
 		if (put_user(sclp_ioctls.echo, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSCOLS:
 		/* set number of columns for output  */
 		if (get_user(sclp_ioctls.columns, (unsigned short __user *) arg))
 			rc = -EFAULT;
 		else
 			check = 1;
 		break;
 	case TIOCSCLPGCOLS:
 		/* get number of columns for output  */
 		if (put_user(sclp_ioctls.columns, (unsigned short __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSNL:
 		/* enable/disable writing without final new line character  */
 		if (get_user(sclp_ioctls.final_nl, (signed char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGNL:
 		/* Is writing without final new line character enabled ?  */
 		if (put_user(sclp_ioctls.final_nl, (signed char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSOBUF:
 		/*
 		 * set the maximum buffers size for output, will be rounded
 		 * up to next 4kB boundary and stored as number of SCCBs
 		 * (4kB Buffers) limitation: 256 x 4kB
 		 */
 		if (get_user(obuf, (unsigned int __user *) arg) == 0) {
 			if (obuf & 0xFFF)
 				sclp_ioctls.max_sccb = (obuf >> 12) + 1;
 			else
 				sclp_ioctls.max_sccb = (obuf >> 12);
 		} else
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGOBUF:
 		/* get the maximum buffers size for output  */
 		obuf = sclp_ioctls.max_sccb << 12;
 		if (put_user(obuf, (unsigned int __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGKBUF:
 		/* get the number of buffers got from kernel at startup */
 		if (put_user(sclp_ioctls.kmem_sccb, (unsigned short __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSCASE:
 		/* enable/disable conversion from upper to lower case */
 		if (get_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGCASE:
 		/* Is conversion from upper to lower case of input enabled? */
 		if (put_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSDELIM:
 		/*
 		 * set special character used for separating upper and
 		 * lower case, 0x00 disables this feature
 		 */
 		if (get_user(sclp_ioctls.delim, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPGDELIM:
 		/*
 		 * get special character used for separating upper and
 		 * lower case, 0x00 disables this feature
 		 */
 		if (put_user(sclp_ioctls.delim, (unsigned char __user *) arg))
 			rc = -EFAULT;
 		break;
 	case TIOCSCLPSINIT:
 		/* set initial (default) sclp ioctls  */
 		sclp_ioctls = sclp_ioctls_init;
 		check = 1;
 		break;
 	default:
 		rc = -ENOIOCTLCMD;
 		break;
 	}
 	if (check) {
 		spin_lock_irqsave(&sclp_tty_lock, flags);
 		if (sclp_ttybuf != NULL) {
 			sclp_set_htab(sclp_ttybuf, sclp_ioctls.htab);
 			sclp_set_columns(sclp_ttybuf, sclp_ioctls.columns);
 		}
 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	}
 	return rc;
 }

 /*
  * This routine returns the numbers of characters the tty driver
  * will accept for queuing to be written.  This number is subject
  * to change as output buffers get emptied, or if the output flow
  * control is acted. This is not an exact number because not every
  * character needs the same space in the sccb. The worst case is
  * a string of newlines. Every newlines creates a new mto which
  * needs 8 bytes.
  */
 static int
 sclp_tty_write_room (struct tty_struct *tty)
 {
 	unsigned long flags;
 	struct list_head *l;
 	int count;

 	spin_lock_irqsave(&sclp_tty_lock, flags);
 	count = 0;
 	if (sclp_ttybuf != NULL)
 		count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct mto);
 	list_for_each(l, &sclp_tty_pages)
 		count += NR_EMPTY_MTO_PER_SCCB;
 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	return count;
 }

 static void
 sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
 {
 	unsigned long flags;
 	void *page;

 	do {
 		page = sclp_unmake_buffer(buffer);
 		spin_lock_irqsave(&sclp_tty_lock, flags);
 		/* Remove buffer from outqueue */
 		list_del(&buffer->list);
 		sclp_tty_buffer_count--;
 		list_add_tail((struct list_head *) page, &sclp_tty_pages);
 		/* Check if there is a pending buffer on the out queue. */
 		buffer = NULL;
 		if (!list_empty(&sclp_tty_outqueue))
 			buffer = list_entry(sclp_tty_outqueue.next,
 					    struct sclp_buffer, list);
 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	} while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
 	wake_up(&sclp_tty_waitq);
 	/* check if the tty needs a wake up call */
 	if (sclp_tty != NULL) {
 		tty_wakeup(sclp_tty);
 	}
 }

 static inline void
 __sclp_ttybuf_emit(struct sclp_buffer *buffer)
 {
 	unsigned long flags;
 	int count;
 	int rc;

 	spin_lock_irqsave(&sclp_tty_lock, flags);
 	list_add_tail(&buffer->list, &sclp_tty_outqueue);
 	count = sclp_tty_buffer_count++;
 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	if (count)
 		return;
 	rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
 	if (rc)
 		sclp_ttybuf_callback(buffer, rc);
 }

 /*
  * When this routine is called from the timer then we flush the
  * temporary write buffer.
  */
 static void
 sclp_tty_timeout(unsigned long data)
 {
 	unsigned long flags;
 	struct sclp_buffer *buf;

 	spin_lock_irqsave(&sclp_tty_lock, flags);
 	buf = sclp_ttybuf;
 	sclp_ttybuf = NULL;
 	spin_unlock_irqrestore(&sclp_tty_lock, flags);

 	if (buf != NULL) {
 		__sclp_ttybuf_emit(buf);
 	}
 }

 /*
  * Write a string to the sclp tty.
  */
 static void
 sclp_tty_write_string(const unsigned char *str, int count)
 {
 	unsigned long flags;
 	void *page;
 	int written;
 	struct sclp_buffer *buf;

 	if (count <= 0)
 		return;
 	spin_lock_irqsave(&sclp_tty_lock, flags);
 	do {
 		/* Create a sclp output buffer if none exists yet */
 		if (sclp_ttybuf == NULL) {
 			while (list_empty(&sclp_tty_pages)) {
 				spin_unlock_irqrestore(&sclp_tty_lock, flags);
 				if (in_interrupt())
 					sclp_sync_wait();
 				else
 					wait_event(sclp_tty_waitq,
 						!list_empty(&sclp_tty_pages));
 				spin_lock_irqsave(&sclp_tty_lock, flags);
 			}
 			page = sclp_tty_pages.next;
 			list_del((struct list_head *) page);
 			sclp_ttybuf = sclp_make_buffer(page,
 						       sclp_ioctls.columns,
 						       sclp_ioctls.htab);
 		}
 		/* try to write the string to the current output buffer */
 		written = sclp_write(sclp_ttybuf, str, count);
 		if (written == count)
 			break;
 		/*
 		 * Not all characters could be written to the current
 		 * output buffer. Emit the buffer, create a new buffer
 		 * and then output the rest of the string.
 		 */
 		buf = sclp_ttybuf;
 		sclp_ttybuf = NULL;
 		spin_unlock_irqrestore(&sclp_tty_lock, flags);
 		__sclp_ttybuf_emit(buf);
 		spin_lock_irqsave(&sclp_tty_lock, flags);
 		str += written;
 		count -= written;
 	} while (count > 0);
 	/* Setup timer to output current console buffer after 1/10 second */
 	if (sclp_ioctls.final_nl) {
 		if (sclp_ttybuf != NULL &&
 		    sclp_chars_in_buffer(sclp_ttybuf) != 0 &&
 		    !timer_pending(&sclp_tty_timer)) {
 			init_timer(&sclp_tty_timer);
 			sclp_tty_timer.function = sclp_tty_timeout;
 			sclp_tty_timer.data = 0UL;
 			sclp_tty_timer.expires = jiffies + HZ/10;
 			add_timer(&sclp_tty_timer);
 		}
 	} else {
 		if (sclp_ttybuf != NULL &&
 		    sclp_chars_in_buffer(sclp_ttybuf) != 0) {
 			buf = sclp_ttybuf;
 			sclp_ttybuf = NULL;
 			spin_unlock_irqrestore(&sclp_tty_lock, flags);
 			__sclp_ttybuf_emit(buf);
 			spin_lock_irqsave(&sclp_tty_lock, flags);
 		}
 	}
 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
 }

 /*
  * This routine is called by the kernel to write a series of characters to the
  * tty device. The characters may come from user space or kernel space. This
  * routine will return the number of characters actually accepted for writing.
  */
 static int
 sclp_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
 	if (sclp_tty_chars_count > 0) {
 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
 		sclp_tty_chars_count = 0;
 	}
 	sclp_tty_write_string(buf, count);
 	return count;
 }

 /*
  * This routine is called by the kernel to write a single character to the tty
  * device. If the kernel uses this routine, it must call the flush_chars()
  * routine (if defined) when it is done stuffing characters into the driver.
  *
  * Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
  * If the given character is a '\n' the contents of the SCLP write buffer
  * - including previous characters from sclp_tty_put_char() and strings from
  * sclp_write() without final '\n' - will be written.
  */
 static void
 sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
 {
 	sclp_tty_chars[sclp_tty_chars_count++] = ch;
 	if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
 		sclp_tty_chars_count = 0;
 	}
 }

 /*
  * This routine is called by the kernel after it has written a series of
  * characters to the tty device using put_char().
  */
 static void
 sclp_tty_flush_chars(struct tty_struct *tty)
 {
 	if (sclp_tty_chars_count > 0) {
 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
 		sclp_tty_chars_count = 0;
 	}
 }

 /*
  * This routine returns the number of characters in the write buffer of the
  * SCLP driver. The provided number includes all characters that are stored
  * in the SCCB (will be written next time the SCLP is not busy) as well as
  * characters in the write buffer (will not be written as long as there is a
  * final line feed missing).
  */
 static int
 sclp_tty_chars_in_buffer(struct tty_struct *tty)
 {
 	unsigned long flags;
 	struct list_head *l;
 	struct sclp_buffer *t;
 	int count;

 	spin_lock_irqsave(&sclp_tty_lock, flags);
 	count = 0;
 	if (sclp_ttybuf != NULL)
 		count = sclp_chars_in_buffer(sclp_ttybuf);
 	list_for_each(l, &sclp_tty_outqueue) {
 		t = list_entry(l, struct sclp_buffer, list);
 		count += sclp_chars_in_buffer(t);
 	}
 	spin_unlock_irqrestore(&sclp_tty_lock, flags);
 	return count;
 }

 /*
  * removes all content from buffers of low level driver
  */
 static void
 sclp_tty_flush_buffer(struct tty_struct *tty)
 {
 	if (sclp_tty_chars_count > 0) {
 		sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
 		sclp_tty_chars_count = 0;
 	}
 }

 /*
  * push input to tty
  */
 static void
 sclp_tty_input(unsigned char* buf, unsigned int count)
 {
 	unsigned int cchar;

 	/*
 	 * If this tty driver is currently closed
 	 * then throw the received input away.
 	 */
 	if (sclp_tty == NULL)
 		return;
 	cchar = ctrlchar_handle(buf, count, sclp_tty);
 	switch (cchar & CTRLCHAR_MASK) {
 	case CTRLCHAR_SYSRQ:
 		break;
 	case CTRLCHAR_CTRL:
 		tty_insert_flip_char(sclp_tty, cchar, TTY_NORMAL);
 		tty_flip_buffer_push(sclp_tty);
 		break;
 	case CTRLCHAR_NONE:
 		/* send (normal) input to line discipline */
 		if (count < 2 ||
 		    (strncmp((const char *) buf + count - 2, "^n", 2) &&
 		     strncmp((const char *) buf + count - 2, "\252n", 2))) {
 			/* add the auto \n */
 			tty_insert_flip_string(sclp_tty, buf, count);
 			tty_insert_flip_char(sclp_tty, '\n', TTY_NORMAL);
 		} else
 			tty_insert_flip_string(sclp_tty, buf, count - 2);
 		tty_flip_buffer_push(sclp_tty);
 		break;
 	}
 }

 /*
  * get a EBCDIC string in upper/lower case,
  * find out characters in lower/upper case separated by a special character,
  * modifiy original string,
  * returns length of resulting string
  */
 static int
 sclp_switch_cases(unsigned char *buf, int count,
 		  unsigned char delim, int tolower)
 {
 	unsigned char *ip, *op;
 	int toggle;

 	/* initially changing case is off */
 	toggle = 0;
 	ip = op = buf;
 	while (count-- > 0) {
 		/* compare with special character */
 		if (*ip == delim) {
 			/* followed by another special character? */
 			if (count && ip[1] == delim) {
 				/*
 				 * ... then put a single copy of the special
 				 * character to the output string
 				 */
 				*op++ = *ip++;
 				count--;
 			} else
 				/*
 				 * ... special character follower by a normal
 				 * character toggles the case change behaviour
 				 */
 				toggle = ~toggle;
 			/* skip special character */
 			ip++;
 		} else
 			/* not the special character */
 			if (toggle)
 				/* but case switching is on */
 				if (tolower)
 					/* switch to uppercase */
 					*op++ = _ebc_toupper[(int) *ip++];
 				else
 					/* switch to lowercase */
 					*op++ = _ebc_tolower[(int) *ip++];
 			else
 				/* no case switching, copy the character */
 				*op++ = *ip++;
 	}
 	/* return length of reformatted string. */
 	return op - buf;
 }

 static void
 sclp_get_input(unsigned char *start, unsigned char *end)
 {
 	int count;

 	count = end - start;
 	/*
 	 * if set in ioctl convert EBCDIC to lower case
 	 * (modify original input in SCCB)
 	 */
 	if (sclp_ioctls.tolower)
 		EBC_TOLOWER(start, count);

 	/*
 	 * if set in ioctl find out characters in lower or upper case
 	 * (depends on current case) separated by a special character,
 	 * works on EBCDIC
 	 */
 	if (sclp_ioctls.delim)
 		count = sclp_switch_cases(start, count,
 					  sclp_ioctls.delim,
 					  sclp_ioctls.tolower);

 	/* convert EBCDIC to ASCII (modify original input in SCCB) */
 	sclp_ebcasc_str(start, count);

 	/* if set in ioctl write operators input to console  */
 	if (sclp_ioctls.echo)
 		sclp_tty_write(sclp_tty, start, count);

 	/* transfer input to high level driver */
 	sclp_tty_input(start, count);
 }

 static inline struct gds_vector *
 find_gds_vector(struct gds_vector *start, struct gds_vector *end, u16 id)
 {
 	struct gds_vector *vec;

 	for (vec = start; vec < end; vec = (void *) vec + vec->length)
 		if (vec->gds_id == id)
 			return vec;
 	return NULL;
 }

 static inline struct gds_subvector *
 find_gds_subvector(struct gds_subvector *start,
 		   struct gds_subvector *end, u8 key)
 {
 	struct gds_subvector *subvec;

 	for (subvec = start; subvec < end;
 	     subvec = (void *) subvec + subvec->length)
 		if (subvec->key == key)
 			return subvec;
 	return NULL;
 }

 static inline void
 sclp_eval_selfdeftextmsg(struct gds_subvector *start,
 			 struct gds_subvector *end)
 {
 	struct gds_subvector *subvec;

 	subvec = start;
 	while (subvec < end) {
 		subvec = find_gds_subvector(subvec, end, 0x30);
 		if (!subvec)
 			break;
 		sclp_get_input((unsigned char *)(subvec + 1),
 			       (unsigned char *) subvec + subvec->length);
 		subvec = (void *) subvec + subvec->length;
 	}
 }

 static inline void
 sclp_eval_textcmd(struct gds_subvector *start,
 		  struct gds_subvector *end)
 {
 	struct gds_subvector *subvec;

 	subvec = start;
 	while (subvec < end) {
 		subvec = find_gds_subvector(subvec, end,
 					    GDS_KEY_SelfDefTextMsg);
 		if (!subvec)
 			break;
 		sclp_eval_selfdeftextmsg((struct gds_subvector *)(subvec + 1),
 					 (void *)subvec + subvec->length);
 		subvec = (void *) subvec + subvec->length;
 	}
 }

 static inline void
 sclp_eval_cpmsu(struct gds_vector *start, struct gds_vector *end)
 {
 	struct gds_vector *vec;

 	vec = start;
 	while (vec < end) {
 		vec = find_gds_vector(vec, end, GDS_ID_TextCmd);
 		if (!vec)
 			break;
 		sclp_eval_textcmd((struct gds_subvector *)(vec + 1),
 				  (void *) vec + vec->length);
 		vec = (void *) vec + vec->length;
 	}
 }


 static inline void
 sclp_eval_mdsmu(struct gds_vector *start, void *end)
 {
 	struct gds_vector *vec;

 	vec = find_gds_vector(start, end, GDS_ID_CPMSU);
 	if (vec)
 		sclp_eval_cpmsu(vec + 1, (void *) vec + vec->length);
 }

 static void
 sclp_tty_receiver(struct evbuf_header *evbuf)
 {
 	struct gds_vector *start, *end, *vec;

 	start = (struct gds_vector *)(evbuf + 1);
 	end = (void *) evbuf + evbuf->length;
 	vec = find_gds_vector(start, end, GDS_ID_MDSMU);
 	if (vec)
 		sclp_eval_mdsmu(vec + 1, (void *) vec + vec->length);
 }

 static void
 sclp_tty_state_change(struct sclp_register *reg)
 {
 }

 static struct sclp_register sclp_input_event =
 {
 	.receive_mask = EvTyp_OpCmd_Mask | EvTyp_PMsgCmd_Mask,
 	.state_change_fn = sclp_tty_state_change,
 	.receiver_fn = sclp_tty_receiver
 };

 static struct tty_operations sclp_ops = {
 	.open = sclp_tty_open,
 	.close = sclp_tty_close,
 	.write = sclp_tty_write,
 	.put_char = sclp_tty_put_char,
 	.flush_chars = sclp_tty_flush_chars,
 	.write_room = sclp_tty_write_room,
 	.chars_in_buffer = sclp_tty_chars_in_buffer,
 	.flush_buffer = sclp_tty_flush_buffer,
 	.ioctl = sclp_tty_ioctl,
 };

 int __init
 sclp_tty_init(void)
 {
 	struct tty_driver *driver;
 	void *page;
 	int i;
 	int rc;

 	if (!CONSOLE_IS_SCLP)
 		return 0;
 	driver = alloc_tty_driver(1);
 	if (!driver)
 		return -ENOMEM;

 	rc = sclp_rw_init();
 	if (rc) {
 		printk(KERN_ERR SCLP_TTY_PRINT_HEADER
 		       "could not register tty - "
 		       "sclp_rw_init returned %d\n", rc);
 		put_tty_driver(driver);
 		return rc;
 	}
 	/* Allocate pages for output buffering */
 	INIT_LIST_HEAD(&sclp_tty_pages);
 	for (i = 0; i < MAX_KMEM_PAGES; i++) {
 		page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 		if (page == NULL) {
 			put_tty_driver(driver);
 			return -ENOMEM;
 		}
 		list_add_tail((struct list_head *) page, &sclp_tty_pages);
 	}
 	INIT_LIST_HEAD(&sclp_tty_outqueue);
 	spin_lock_init(&sclp_tty_lock);
 	init_waitqueue_head(&sclp_tty_waitq);
 	init_timer(&sclp_tty_timer);
 	sclp_ttybuf = NULL;
 	sclp_tty_buffer_count = 0;
 	if (MACHINE_IS_VM) {
 		/*
 		 * save 4 characters for the CPU number
 		 * written at start of each line by VM/CP
 		 */
 		sclp_ioctls_init.columns = 76;
 		/* case input lines to lowercase */
 		sclp_ioctls_init.tolower = 1;
 	}
 	sclp_ioctls = sclp_ioctls_init;
 	sclp_tty_chars_count = 0;
 	sclp_tty = NULL;

 	rc = sclp_register(&sclp_input_event);
 	if (rc) {
 		put_tty_driver(driver);
 		return rc;
 	}

 	driver->owner = THIS_MODULE;
 	driver->driver_name = "sclp_line";
 	driver->name = "sclp_line";
 	driver->major = TTY_MAJOR;
 	driver->minor_start = 64;
 	driver->type = TTY_DRIVER_TYPE_SYSTEM;
 	driver->subtype = SYSTEM_TYPE_TTY;
 	driver->init_termios = tty_std_termios;
 	driver->init_termios.c_iflag = IGNBRK | IGNPAR;
 	driver->init_termios.c_oflag = ONLCR | XTABS;
 	driver->init_termios.c_lflag = ISIG | ECHO;
 	driver->flags = TTY_DRIVER_REAL_RAW;
 	tty_set_operations(driver, &sclp_ops);
 	rc = tty_register_driver(driver);
 	if (rc) {
 		printk(KERN_ERR SCLP_TTY_PRINT_HEADER
 		       "could not register tty - "
 		       "tty_register_driver returned %d\n", rc);
 		put_tty_driver(driver);
 		return rc;
 	}
 	sclp_tty_driver = driver;
 	return 0;
 }
 module_init(sclp_tty_init);
	/*
	* drivers/s390/char/sclp_tty.c
	* SCLP line mode terminal driver.
	*
	* S390 version
	* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
	* Author(s): Martin Peschke <mpeschke@de.ibm.com>
	* Martin Schwidefsky <schwidefsky@de.ibm.com>
	*/

	#include <linux/module.h>
	#include <linux/kmod.h>
	#include <linux/tty.h>
	#include <linux/tty_driver.h>
	#include <linux/tty_flip.h>
	#include <linux/sched.h>
	#include <linux/wait.h>
	#include <linux/slab.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <asm/uaccess.h>

	#include "ctrlchar.h"
	#include "sclp.h"
	#include "sclp_rw.h"
	#include "sclp_tty.h"

	#define SCLP_TTY_PRINT_HEADER "sclp tty driver: "

	/*
	* size of a buffer that collects single characters coming in
	* via sclp_tty_put_char()
	*/
	#define SCLP_TTY_BUF_SIZE 512

	/*
	* There is exactly one SCLP terminal, so we can keep things simple
	* and allocate all variables statically.
	*/

	/* Lock to guard over changes to global variables. */
	static spinlock_t sclp_tty_lock;
	/* List of free pages that can be used for console output buffering. */
	static struct list_head sclp_tty_pages;
	/* List of full struct sclp_buffer structures ready for output. */
	static struct list_head sclp_tty_outqueue;
	/* Counter how many buffers are emitted. */
	static int sclp_tty_buffer_count;
	/* Pointer to current console buffer. */
	static struct sclp_buffer *sclp_ttybuf;
	/* Timer for delayed output of console messages. */
	static struct timer_list sclp_tty_timer;
	/* Waitqueue to wait for buffers to get empty. */
	static wait_queue_head_t sclp_tty_waitq;

	static struct tty_struct *sclp_tty;
	static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
	static unsigned short int sclp_tty_chars_count;

	struct tty_driver *sclp_tty_driver;

	extern struct termios tty_std_termios;

	static struct sclp_ioctls sclp_ioctls;
	static struct sclp_ioctls sclp_ioctls_init =
	{
	8, /* 1 hor. tab. = 8 spaces */
	0, /* no echo of input by this driver */
	80, /* 80 characters/line */
	1, /* write after 1/10 s without final new line */
	MAX_KMEM_PAGES, /* quick fix: avoid __alloc_pages */
	MAX_KMEM_PAGES, /* take 32/64 pages from kernel memory, */
	0, /* do not convert to lower case */
	0x6c /* to seprate upper and lower case */
	/* ('%' in EBCDIC) */
	};

	/* This routine is called whenever we try to open a SCLP terminal. */
	static int
	sclp_tty_open(struct tty_struct tty, struct file filp)
	{
	sclp_tty = tty;
	tty->driver_data = NULL;
	tty->low_latency = 0;
	return 0;
	}

	/* This routine is called when the SCLP terminal is closed. */
	static void
	sclp_tty_close(struct tty_struct tty, struct file filp)
	{
	if (tty->count > 1)
	return;
	sclp_tty = NULL;
	}

	/* execute commands to control the i/o behaviour of the SCLP tty at runtime */
	static int
	sclp_tty_ioctl(struct tty_struct tty, struct file file,
	unsigned int cmd, unsigned long arg)
	{
	unsigned long flags;
	unsigned int obuf;
	int check;
	int rc;

	if (tty->flags & (1 << TTY_IO_ERROR))
	return -EIO;
	rc = 0;
	check = 0;
	switch (cmd) {
	case TIOCSCLPSHTAB:
	/* set width of horizontal tab */
	if (get_user(sclp_ioctls.htab, (unsigned short __user *) arg))
	rc = -EFAULT;
	else
	check = 1;
	break;
	case TIOCSCLPGHTAB:
	/* get width of horizontal tab */
	if (put_user(sclp_ioctls.htab, (unsigned short __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSECHO:
	/* enable/disable echo of input */
	if (get_user(sclp_ioctls.echo, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPGECHO:
	/* Is echo of input enabled ? */
	if (put_user(sclp_ioctls.echo, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSCOLS:
	/* set number of columns for output */
	if (get_user(sclp_ioctls.columns, (unsigned short __user *) arg))
	rc = -EFAULT;
	else
	check = 1;
	break;
	case TIOCSCLPGCOLS:
	/* get number of columns for output */
	if (put_user(sclp_ioctls.columns, (unsigned short __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSNL:
	/* enable/disable writing without final new line character */
	if (get_user(sclp_ioctls.final_nl, (signed char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPGNL:
	/* Is writing without final new line character enabled ? */
	if (put_user(sclp_ioctls.final_nl, (signed char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSOBUF:
	/*
	* set the maximum buffers size for output, will be rounded
	* up to next 4kB boundary and stored as number of SCCBs
	* (4kB Buffers) limitation: 256 x 4kB
	*/
	if (get_user(obuf, (unsigned int __user *) arg) == 0) {
	if (obuf & 0xFFF)
	sclp_ioctls.max_sccb = (obuf >> 12) + 1;
	else
	sclp_ioctls.max_sccb = (obuf >> 12);
	} else
	rc = -EFAULT;
	break;
	case TIOCSCLPGOBUF:
	/* get the maximum buffers size for output */
	obuf = sclp_ioctls.max_sccb << 12;
	if (put_user(obuf, (unsigned int __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPGKBUF:
	/* get the number of buffers got from kernel at startup */
	if (put_user(sclp_ioctls.kmem_sccb, (unsigned short __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSCASE:
	/* enable/disable conversion from upper to lower case */
	if (get_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPGCASE:
	/* Is conversion from upper to lower case of input enabled? */
	if (put_user(sclp_ioctls.tolower, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSDELIM:
	/*
	* set special character used for separating upper and
	* lower case, 0x00 disables this feature
	*/
	if (get_user(sclp_ioctls.delim, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPGDELIM:
	/*
	* get special character used for separating upper and
	* lower case, 0x00 disables this feature
	*/
	if (put_user(sclp_ioctls.delim, (unsigned char __user *) arg))
	rc = -EFAULT;
	break;
	case TIOCSCLPSINIT:
	/* set initial (default) sclp ioctls */
	sclp_ioctls = sclp_ioctls_init;
	check = 1;
	break;
	default:
	rc = -ENOIOCTLCMD;
	break;
	}
	if (check) {
	spin_lock_irqsave(&sclp_tty_lock, flags);
	if (sclp_ttybuf != NULL) {
	sclp_set_htab(sclp_ttybuf, sclp_ioctls.htab);
	sclp_set_columns(sclp_ttybuf, sclp_ioctls.columns);
	}
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	}
	return rc;
	}

	/*
	* This routine returns the numbers of characters the tty driver
	* will accept for queuing to be written. This number is subject
	* to change as output buffers get emptied, or if the output flow
	* control is acted. This is not an exact number because not every
	* character needs the same space in the sccb. The worst case is
	* a string of newlines. Every newlines creates a new mto which
	* needs 8 bytes.
	*/
	static int
	sclp_tty_write_room (struct tty_struct *tty)
	{
	unsigned long flags;
	struct list_head *l;
	int count;

	spin_lock_irqsave(&sclp_tty_lock, flags);
	count = 0;
	if (sclp_ttybuf != NULL)
	count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct mto);
	list_for_each(l, &sclp_tty_pages)
	count += NR_EMPTY_MTO_PER_SCCB;
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	return count;
	}

	static void
	sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
	{
	unsigned long flags;
	void *page;

	do {
	page = sclp_unmake_buffer(buffer);
	spin_lock_irqsave(&sclp_tty_lock, flags);
	/* Remove buffer from outqueue */
	list_del(&buffer->list);
	sclp_tty_buffer_count--;
	list_add_tail((struct list_head *) page, &sclp_tty_pages);
	/* Check if there is a pending buffer on the out queue. */
	buffer = NULL;
	if (!list_empty(&sclp_tty_outqueue))
	buffer = list_entry(sclp_tty_outqueue.next,
	struct sclp_buffer, list);
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	} while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
	wake_up(&sclp_tty_waitq);
	/* check if the tty needs a wake up call */
	if (sclp_tty != NULL) {
	tty_wakeup(sclp_tty);
	}
	}

	static inline void
	__sclp_ttybuf_emit(struct sclp_buffer *buffer)
	{
	unsigned long flags;
	int count;
	int rc;

	spin_lock_irqsave(&sclp_tty_lock, flags);
	list_add_tail(&buffer->list, &sclp_tty_outqueue);
	count = sclp_tty_buffer_count++;
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	if (count)
	return;
	rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
	if (rc)
	sclp_ttybuf_callback(buffer, rc);
	}

	/*
	* When this routine is called from the timer then we flush the
	* temporary write buffer.
	*/
	static void
	sclp_tty_timeout(unsigned long data)
	{
	unsigned long flags;
	struct sclp_buffer *buf;

	spin_lock_irqsave(&sclp_tty_lock, flags);
	buf = sclp_ttybuf;
	sclp_ttybuf = NULL;
	spin_unlock_irqrestore(&sclp_tty_lock, flags);

	if (buf != NULL) {
	__sclp_ttybuf_emit(buf);
	}
	}

	/*
	* Write a string to the sclp tty.
	*/
	static void
	sclp_tty_write_string(const unsigned char *str, int count)
	{
	unsigned long flags;
	void *page;
	int written;
	struct sclp_buffer *buf;

	if (count <= 0)
	return;
	spin_lock_irqsave(&sclp_tty_lock, flags);
	do {
	/* Create a sclp output buffer if none exists yet */
	if (sclp_ttybuf == NULL) {
	while (list_empty(&sclp_tty_pages)) {
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	if (in_interrupt())
	sclp_sync_wait();
	else
	wait_event(sclp_tty_waitq,
	!list_empty(&sclp_tty_pages));
	spin_lock_irqsave(&sclp_tty_lock, flags);
	}
	page = sclp_tty_pages.next;
	list_del((struct list_head *) page);
	sclp_ttybuf = sclp_make_buffer(page,
	sclp_ioctls.columns,
	sclp_ioctls.htab);
	}
	/* try to write the string to the current output buffer */
	written = sclp_write(sclp_ttybuf, str, count);
	if (written == count)
	break;
	/*
	* Not all characters could be written to the current
	* output buffer. Emit the buffer, create a new buffer
	* and then output the rest of the string.
	*/
	buf = sclp_ttybuf;
	sclp_ttybuf = NULL;
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	__sclp_ttybuf_emit(buf);
	spin_lock_irqsave(&sclp_tty_lock, flags);
	str += written;
	count -= written;
	} while (count > 0);
	/* Setup timer to output current console buffer after 1/10 second */
	if (sclp_ioctls.final_nl) {
	if (sclp_ttybuf != NULL &&
	sclp_chars_in_buffer(sclp_ttybuf) != 0 &&
	!timer_pending(&sclp_tty_timer)) {
	init_timer(&sclp_tty_timer);
	sclp_tty_timer.function = sclp_tty_timeout;
	sclp_tty_timer.data = 0UL;
	sclp_tty_timer.expires = jiffies + HZ/10;
	add_timer(&sclp_tty_timer);
	}
	} else {
	if (sclp_ttybuf != NULL &&
	sclp_chars_in_buffer(sclp_ttybuf) != 0) {
	buf = sclp_ttybuf;
	sclp_ttybuf = NULL;
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	__sclp_ttybuf_emit(buf);
	spin_lock_irqsave(&sclp_tty_lock, flags);
	}
	}
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	}

	/*
	* This routine is called by the kernel to write a series of characters to the
	* tty device. The characters may come from user space or kernel space. This
	* routine will return the number of characters actually accepted for writing.
	*/
	static int
	sclp_tty_write(struct tty_struct tty, const unsigned char buf, int count)
	{
	if (sclp_tty_chars_count > 0) {
	sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
	sclp_tty_chars_count = 0;
	}
	sclp_tty_write_string(buf, count);
	return count;
	}

	/*
	* This routine is called by the kernel to write a single character to the tty
	* device. If the kernel uses this routine, it must call the flush_chars()
	* routine (if defined) when it is done stuffing characters into the driver.
	*
	* Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
	* If the given character is a '\n' the contents of the SCLP write buffer
	* - including previous characters from sclp_tty_put_char() and strings from
	* sclp_write() without final '\n' - will be written.
	*/
	static void
	sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
	{
	sclp_tty_chars[sclp_tty_chars_count++] = ch;
	if (ch == '\n' \|\| sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
	sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
	sclp_tty_chars_count = 0;
	}
	}

	/*
	* This routine is called by the kernel after it has written a series of
	* characters to the tty device using put_char().
	*/
	static void
	sclp_tty_flush_chars(struct tty_struct *tty)
	{
	if (sclp_tty_chars_count > 0) {
	sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
	sclp_tty_chars_count = 0;
	}
	}

	/*
	* This routine returns the number of characters in the write buffer of the
	* SCLP driver. The provided number includes all characters that are stored
	* in the SCCB (will be written next time the SCLP is not busy) as well as
	* characters in the write buffer (will not be written as long as there is a
	* final line feed missing).
	*/
	static int
	sclp_tty_chars_in_buffer(struct tty_struct *tty)
	{
	unsigned long flags;
	struct list_head *l;
	struct sclp_buffer *t;
	int count;

	spin_lock_irqsave(&sclp_tty_lock, flags);
	count = 0;
	if (sclp_ttybuf != NULL)
	count = sclp_chars_in_buffer(sclp_ttybuf);
	list_for_each(l, &sclp_tty_outqueue) {
	t = list_entry(l, struct sclp_buffer, list);
	count += sclp_chars_in_buffer(t);
	}
	spin_unlock_irqrestore(&sclp_tty_lock, flags);
	return count;
	}

	/*
	* removes all content from buffers of low level driver
	*/
	static void
	sclp_tty_flush_buffer(struct tty_struct *tty)
	{
	if (sclp_tty_chars_count > 0) {
	sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count);
	sclp_tty_chars_count = 0;
	}
	}

	/*
	* push input to tty
	*/
	static void
	sclp_tty_input(unsigned char* buf, unsigned int count)
	{
	unsigned int cchar;

	/*
	* If this tty driver is currently closed
	* then throw the received input away.
	*/
	if (sclp_tty == NULL)
	return;
	cchar = ctrlchar_handle(buf, count, sclp_tty);
	switch (cchar & CTRLCHAR_MASK) {
	case CTRLCHAR_SYSRQ:
	break;
	case CTRLCHAR_CTRL:
	tty_insert_flip_char(sclp_tty, cchar, TTY_NORMAL);
	tty_flip_buffer_push(sclp_tty);
	break;
	case CTRLCHAR_NONE:
	/* send (normal) input to line discipline */
	if (count < 2 \|\|
	(strncmp((const char *) buf + count - 2, "^n", 2) &&
	strncmp((const char *) buf + count - 2, "\252n", 2))) {
	/* add the auto \n */
	tty_insert_flip_string(sclp_tty, buf, count);
	tty_insert_flip_char(sclp_tty, '\n', TTY_NORMAL);
	} else
	tty_insert_flip_string(sclp_tty, buf, count - 2);
	tty_flip_buffer_push(sclp_tty);
	break;
	}
	}

	/*
	* get a EBCDIC string in upper/lower case,
	* find out characters in lower/upper case separated by a special character,
	* modifiy original string,
	* returns length of resulting string
	*/
	static int
	sclp_switch_cases(unsigned char *buf, int count,
	unsigned char delim, int tolower)
	{
	unsigned char ip, op;
	int toggle;

	/* initially changing case is off */
	toggle = 0;
	ip = op = buf;
	while (count-- > 0) {
	/* compare with special character */
	if (*ip == delim) {
	/* followed by another special character? */
	if (count && ip[1] == delim) {
	/*
	* ... then put a single copy of the special
	* character to the output string
	*/
	op++ = ip++;
	count--;
	} else
	/*
	* ... special character follower by a normal
	* character toggles the case change behaviour
	*/
	toggle = ~toggle;
	/* skip special character */
	ip++;
	} else
	/* not the special character */
	if (toggle)
	/* but case switching is on */
	if (tolower)
	/* switch to uppercase */
	op++ = _ebc_toupper[(int) ip++];
	else
	/* switch to lowercase */
	op++ = _ebc_tolower[(int) ip++];
	else
	/* no case switching, copy the character */
	op++ = ip++;
	}
	/* return length of reformatted string. */
	return op - buf;
	}

	static void
	sclp_get_input(unsigned char start, unsigned char end)
	{
	int count;

	count = end - start;
	/*
	* if set in ioctl convert EBCDIC to lower case
	* (modify original input in SCCB)
	*/
	if (sclp_ioctls.tolower)
	EBC_TOLOWER(start, count);

	/*
	* if set in ioctl find out characters in lower or upper case
	* (depends on current case) separated by a special character,
	* works on EBCDIC
	*/
	if (sclp_ioctls.delim)
	count = sclp_switch_cases(start, count,
	sclp_ioctls.delim,
	sclp_ioctls.tolower);

	/* convert EBCDIC to ASCII (modify original input in SCCB) */
	sclp_ebcasc_str(start, count);

	/* if set in ioctl write operators input to console */
	if (sclp_ioctls.echo)
	sclp_tty_write(sclp_tty, start, count);

	/* transfer input to high level driver */
	sclp_tty_input(start, count);
	}

	static inline struct gds_vector *
	find_gds_vector(struct gds_vector start, struct gds_vector end, u16 id)
	{
	struct gds_vector *vec;

	for (vec = start; vec < end; vec = (void *) vec + vec->length)
	if (vec->gds_id == id)
	return vec;
	return NULL;
	}

	static inline struct gds_subvector *
	find_gds_subvector(struct gds_subvector *start,
	struct gds_subvector *end, u8 key)
	{
	struct gds_subvector *subvec;

	for (subvec = start; subvec < end;
	subvec = (void *) subvec + subvec->length)
	if (subvec->key == key)
	return subvec;
	return NULL;
	}

	static inline void
	sclp_eval_selfdeftextmsg(struct gds_subvector *start,
	struct gds_subvector *end)
	{
	struct gds_subvector *subvec;

	subvec = start;
	while (subvec < end) {
	subvec = find_gds_subvector(subvec, end, 0x30);
	if (!subvec)
	break;
	sclp_get_input((unsigned char *)(subvec + 1),
	(unsigned char *) subvec + subvec->length);
	subvec = (void *) subvec + subvec->length;
	}
	}

	static inline void
	sclp_eval_textcmd(struct gds_subvector *start,
	struct gds_subvector *end)
	{
	struct gds_subvector *subvec;

	subvec = start;
	while (subvec < end) {
	subvec = find_gds_subvector(subvec, end,
	GDS_KEY_SelfDefTextMsg);
	if (!subvec)
	break;
	sclp_eval_selfdeftextmsg((struct gds_subvector *)(subvec + 1),
	(void *)subvec + subvec->length);
	subvec = (void *) subvec + subvec->length;
	}
	}

	static inline void
	sclp_eval_cpmsu(struct gds_vector start, struct gds_vector end)
	{
	struct gds_vector *vec;

	vec = start;
	while (vec < end) {
	vec = find_gds_vector(vec, end, GDS_ID_TextCmd);
	if (!vec)
	break;
	sclp_eval_textcmd((struct gds_subvector *)(vec + 1),
	(void *) vec + vec->length);
	vec = (void *) vec + vec->length;
	}
	}


	static inline void
	sclp_eval_mdsmu(struct gds_vector start, void end)
	{
	struct gds_vector *vec;

	vec = find_gds_vector(start, end, GDS_ID_CPMSU);
	if (vec)
	sclp_eval_cpmsu(vec + 1, (void *) vec + vec->length);
	}

	static void
	sclp_tty_receiver(struct evbuf_header *evbuf)
	{
	struct gds_vector start, end, *vec;

	start = (struct gds_vector *)(evbuf + 1);
	end = (void *) evbuf + evbuf->length;
	vec = find_gds_vector(start, end, GDS_ID_MDSMU);
	if (vec)
	sclp_eval_mdsmu(vec + 1, (void *) vec + vec->length);
	}

	static void
	sclp_tty_state_change(struct sclp_register *reg)
	{
	}

	static struct sclp_register sclp_input_event =
	{
	.receive_mask = EvTyp_OpCmd_Mask \| EvTyp_PMsgCmd_Mask,
	.state_change_fn = sclp_tty_state_change,
	.receiver_fn = sclp_tty_receiver
	};

	static struct tty_operations sclp_ops = {
	.open = sclp_tty_open,
	.close = sclp_tty_close,
	.write = sclp_tty_write,
	.put_char = sclp_tty_put_char,
	.flush_chars = sclp_tty_flush_chars,
	.write_room = sclp_tty_write_room,
	.chars_in_buffer = sclp_tty_chars_in_buffer,
	.flush_buffer = sclp_tty_flush_buffer,
	.ioctl = sclp_tty_ioctl,
	};

	int __init
	sclp_tty_init(void)
	{
	struct tty_driver *driver;
	void *page;
	int i;
	int rc;

	if (!CONSOLE_IS_SCLP)
	return 0;
	driver = alloc_tty_driver(1);
	if (!driver)
	return -ENOMEM;

	rc = sclp_rw_init();
	if (rc) {
	printk(KERN_ERR SCLP_TTY_PRINT_HEADER
	"could not register tty - "
	"sclp_rw_init returned %d\n", rc);
	put_tty_driver(driver);
	return rc;
	}
	/* Allocate pages for output buffering */
	INIT_LIST_HEAD(&sclp_tty_pages);
	for (i = 0; i < MAX_KMEM_PAGES; i++) {
	page = (void *) get_zeroed_page(GFP_KERNEL \| GFP_DMA);
	if (page == NULL) {
	put_tty_driver(driver);
	return -ENOMEM;
	}
	list_add_tail((struct list_head *) page, &sclp_tty_pages);
	}
	INIT_LIST_HEAD(&sclp_tty_outqueue);
	spin_lock_init(&sclp_tty_lock);
	init_waitqueue_head(&sclp_tty_waitq);
	init_timer(&sclp_tty_timer);
	sclp_ttybuf = NULL;
	sclp_tty_buffer_count = 0;
	if (MACHINE_IS_VM) {
	/*
	* save 4 characters for the CPU number
	* written at start of each line by VM/CP
	*/
	sclp_ioctls_init.columns = 76;
	/* case input lines to lowercase */
	sclp_ioctls_init.tolower = 1;
	}
	sclp_ioctls = sclp_ioctls_init;
	sclp_tty_chars_count = 0;
	sclp_tty = NULL;

	rc = sclp_register(&sclp_input_event);
	if (rc) {
	put_tty_driver(driver);
	return rc;
	}

	driver->owner = THIS_MODULE;
	driver->driver_name = "sclp_line";
	driver->name = "sclp_line";
	driver->major = TTY_MAJOR;
	driver->minor_start = 64;
	driver->type = TTY_DRIVER_TYPE_SYSTEM;
	driver->subtype = SYSTEM_TYPE_TTY;
	driver->init_termios = tty_std_termios;
	driver->init_termios.c_iflag = IGNBRK \| IGNPAR;
	driver->init_termios.c_oflag = ONLCR \| XTABS;
	driver->init_termios.c_lflag = ISIG \| ECHO;
	driver->flags = TTY_DRIVER_REAL_RAW;
	tty_set_operations(driver, &sclp_ops);
	rc = tty_register_driver(driver);
	if (rc) {
	printk(KERN_ERR SCLP_TTY_PRINT_HEADER
	"could not register tty - "
	"tty_register_driver returned %d\n", rc);
	put_tty_driver(driver);
	return rc;
	}
	sclp_tty_driver = driver;
	return 0;
	}
	module_init(sclp_tty_init);